Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include "bits/stdc++.h"
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
const int MOD = 1e9+7;
const int larg = 1e5;

typedef pair<int, int> P;
typedef long long ll;

int main() {
	int H, W, white_point = 0;
	cin >> H >> W;
	char map[51][51];
	int count[51][51];
	rep(i, H){
		rep(j, W){
			cin >> map[i][j];
			count[i][j] = -1;
			if(map[i][j] == '.') white_point++; 
		}
	}
	int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};
	queue<P> que;
	que.push(P(0,0));
	count[0][0] = 1;
	while(!que.empty()){
		P p = que.front(); que.pop();
		int x = p.first, y = p.second;
		rep(i, 4){
			int nx = x+dx[i], ny = y+dy[i];
			if(-1 < ny && ny < H && -1 < nx && nx < W && map[ny][nx] != '#' && count[ny][nx] == -1) {
				que.push(P(nx,ny));
				count[ny][nx] = count[y][x]+1;
			}
		}
	}
	if(count[H-1][W-1] == -1) cout << -1;
	else cout << white_point-count[H-1][W-1];
}